Liquid discharge head and liquid discharge apparatus using liquid discharge head

ABSTRACT

In order to provide a compact and highly reliable recording head enabling precise detection of temperature information on each nozzle and rapid as well as highly accurate detection on nozzles with a discharge defect, a liquid discharge head including a liquid discharge head with a plurality of electrothermal transducing members provided on a substrate to generate heat energy for discharging liquid from a discharge port includes a temperature detecting element formed immediately under each of the plurality of electrothermal transducing members to sandwich insulating film and a temperature detecting circuit for detecting temperature information from each of the temperature detecting elements.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a liquid discharge head and a liquiddischarge apparatus using the liquid discharge head.

2. Description of the Related Art

An ink jet printer (ink jet recording apparatus) is now being widelyused as a liquid discharge apparatus. An ink jet head is used as aliquid discharge head in that printer. That ink jet head is based onvarious types of liquid discharge principles. The widespread type inparticular is an ink jet head applying thermal energy to ink todischarge ink drops from a discharge port. That type of ink jet head isadvantageous in that responsiveness to record signals is good andenhancement in high density of the discharge port on a multilevel basisis easy.

However, in an ink jet printer (ink jet recording apparatus) with suchan ink jet head, foreign material occasionally blocks the discharge portor bubbles mixed into inside the ink supply route occasionally blocksthe ink supply route thereof. An occurrence of such events will resultin ink discharge defects of an ink jet head. In particular, a so-calledfull-line type recording apparatus provided with a great number ofdischarge ports being arranged in a lined state enabling ink jetrecording corresponding with the entire width of recording media enablesrapid recording execution. Nevertheless, it is extremely important tospecify the discharge port (discharge nozzle) having caused dischargedefects rapidly to be reflected onto image complementation and inkdischarge recovering work.

Technology for solution of such discharge defects is known.

Japanese Patent Application Laid-Open No. H6-079956 describes arecording method, moving image data to be given to an abnormal recordingelement to image data to be given to another recording element even inan occurrence of abnormality in a recording element and thereby causingthat another recording element to complement the record. However, thatrecording method carries out processing of reading a check patterndischarged onto a detection sheet to detect an abnormal recordingelement and to superpose image data to be added to that detectedrecording element onto image data of another recording element. Thatprocessing is applicable to a recording apparatus with slow responsespeed but is hardly applicable to a recording element with fast responsespeed such as a full-line type recording apparatus.

Moreover, Japanese Patent Application Laid-open No. H2-276647 describesa recording apparatus for detecting a discharge port having caseddischarge defects in a line-type recording head to carry out recordingwith a serial type recording head on a recording position correspondingwith that discharge port. However, that discharge defect detectionmethod detects transmits a heat timing signal to a heat generatingresistor member, detects a signal flowing in the heat generatingresistor member at that occasion to detect whether or not the heatresistor member is broken.

Moreover, Japanese Patent Application Laid-Open No. S58-118267 describeda recording head as illustrated in FIG. 16. There described is a liquiddischarge apparatus provided with a temperature change detectingconductor portion 102 inside a flow channel (inside a nozzle) betweenadjacent electrothermal energy transducing members 101, including aplurality of nozzles 100 arranged in a row. Moreover, there alsodescribed is a liquid discharge apparatus provided with a conductorportion 102 on the rear surface of the side opposite to the surface of asubstrate 103 provided with an electrothermal energy transducing member101 and in a position corresponding with a nozzle 100. However, the casewhere the conductor portion 102 is provided sideway of theelectrothermal energy transducing member 101 is susceptible to influenceof heat of the adjacent electrothermal energy transducing member and issusceptible to influence covering thickness of the substrate 103 in thecase of providing the conductor portion 102 on the rear surface side ofthe substrate 103. Therefore, it becomes difficult to precisely detecttemperature changes occurring due to repetition of rapid temperatureincrease and decrease within an extremely short time period.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a compact and highlyreliable recording head enabling precise detection of temperatureinformation on each nozzle and rapid as well as highly accuratedetection on nozzles with a discharge defect.

Another object of the present invention is to provide a liquid dischargehead including a plurality of electrothermal transducing membersprovided on a substrate to generate heat energy for discharging liquidfrom a discharge port, including a temperature detecting element formedimmediately under each of the plurality of electrothermal transducingmembers to sandwich insulating film; and a temperature detecting circuitfor detecting temperature information from each of the temperaturedetecting elements.

Further features of the present invention will become apparent from thefollowing description of exemplary embodiments with reference to theattached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view of a recording head mounted on a recordingapparatus being a first embodiment of the present invention.

FIG. 2 is a plan view of the recording head mounted on the recordingapparatus being the first embodiment of the present invention.

FIG. 3 is a condition chart illustrating temperature profiles on an inkinterface of cavitation-resistant film in the recording head mounted onthe recording apparatus being the first embodiment of the presentinvention.

FIG. 4 is a condition chart illustrating temperature profiles in atemperature detecting element of the recording head mounted on therecording apparatus being the first embodiment of the present invention.

FIGS. 5A and 5B are condition charts illustrating temperature profilesas simulations on an arrangement position of a temperature detectingelement.

FIG. 6 is a block diagram illustrating a schematic configuration of aheater control circuit and the temperature detecting circuit applied tothe recording head illustrated in FIG. 1 and FIG. 2.

FIG. 7 is a timing chart illustrating operations of the heater controlcircuit illustrated in FIG. 6.

FIG. 8 is a block diagram illustrating a configuration of a circuit, towhich the temperature of detecting circuit illustrated in FIG. 6,outputting a determination signal notifying non-discharge.

FIG. 9 is a plan view illustrating another shape of the temperature ofdetecting element used in the recording head mounted on the recordingapparatus being the first embodiment of the present invention.

FIG. 10 is a plan view of a recording head mounted on a recordingapparatus being a second embodiment of the present invention.

FIG. 11 is a block diagram illustrating a schematic configuration of acontrol circuit and a temperature detecting circuit applied to therecording head illustrated in FIG. 10.

FIG. 12 is a timing chart illustrating operations of the control circuitillustrated in FIG. 11.

FIG. 13 is a block diagram illustrating a configuration of a circuit, towhich the temperature detecting circuit illustrated in FIG. 11 isapplied, for outputting determination signals.

FIG. 14 is a plan view illustrating another shape of the temperature ofdetecting element used in the recording head mounted on the recordingapparatus being the second embodiment of the present invention.

FIG. 15 is a block diagram illustrating a configuration of a circuitapplied to the recording apparatus being the second embodiment of thepresent invention for transducing temperature information to digitalvalues.

FIG. 16 is a perspective view illustrating major portions of a recordingapparatus of a prior art.

DESCRIPTION OF THE EMBODIMENTS

Next, embodiments of the present invention will be described withreference to drawings.

First Embodiment

FIG. 1 and FIG. 2 are a sectional view and a plan view respectively of arecording head mounted on a recording apparatus being a first embodimentof the present invention. In FIG. 1 and FIG. 2, a discharge nozzleportion including a discharge port, a liquid route and the like isomitted.

With reference to FIG. 1, a heat accumulating layer is formed on a Sisubstrate 1. A plurality of temperature detecting elements 3 is formedon the heat accumulating layer 2. A plurality of heaters 5 is formed onthe heat accumulating layer 2 in which the temperature detecting element3 is formed to sandwich interlayer insulating film 4. Moreover,cavitation-resistant film 7 is formed on the surface where the heaters 5are formed to sandwich passivation film 6. Respective layers selectedfrom the group including the heat accumulating layer 2, the temperaturedetecting element 3, the interlayer insulating film 4, the heaters 5,the passivation film 6, the cavitation-resistant film 7 are highlydensely stacked with known semiconductor processing.

The heat accumulating layer 2 is a thermally-oxidized film such as SiO₂.The temperature detecting element 3 includes thin film resistor memberselected from the group including Al, AlCu, Pt, Ti, TiN, TiSi, Ta, TaN,TaSiN, TaCr, Cr, CrSiN, W. The heaters 5 include an electrothermaltransducing member such as TaSiN. The passivation film 6 includes SiO₂and the like. The cavitation-resistant film 7 intensifiescavitation-resistant properties of the heaters 5. The thin film resistormember included in the temperature detecting element 3 is formedseparately and independently immediately below the electrothermaltransducing member included in each heaters 5.

The temperature detecting elements 3 and the heaters 5 are allrectangular as illustrated in FIG. 2. The area of a temperaturedetecting element 3 is larger than the area of a heater 5. In the caseof viewing the heaters 5 from the upper side of the Si substrate 1, theheater 5 is positioned approximately in the center of the temperaturedetecting element 3. An end (terminal) of the temperature detectingelement 3 is connected to individual wiring 31. The other end (terminal)is connected to common wiring 32. The individual wiring 31 and thecommon wiring 32 made of Al and the like and is formed together with thetemperature detecting element 3 on the Si substrate 1. Here, circuitsselected from the group including a switching element, a controlcircuit, a circuit for detecting temperature are not illustrated in FIG.1 and FIG. 2 but are formed on the Si substrate 1 in order to controlthe temperature detecting element 3 and heaters 5.

According to the recording head of the present embodiment, thetemperature detecting element 3 is formed immediately under the heaters5 (between the heaters 5 and the Si substrate 1). Therefore thetemperature changes due to heat dissipation from the heaters 5 can bedetected rapidly and accurately. In addition, the condition havingdischarged ink normally and the condition with non-discharge of ink canbe determined precisely. The reasons will be described belowspecifically.

At first, the temperature changes in the ink interface of thecavitation-resistant film 7 will be described when the heaters 5 undergoand off operations. FIG. 3 is a condition chart illustrating temperatureprofiles on an ink interface of cavitation-resistant film. FIG. 3illustrates the temperature profiles in the case where ink is dischargednormally and in the case of ink non-discharge respectively. Both of thetemperature profiles illustrate the result obtained by temperaturesimulation with a computer.

In the case of the normal discharge, the heater 5 increases temperaturefrom the point of time (timing to supply an application start signal t0)when electric energy is applied to an electrothermal transducing memberincluded in the heater 5. Corresponding therewith, the temperature riseson the ink interface between the cavitation-resistant film 7 and the ink(condition I). The interface temperature of the cavitation-resistantfilm 7 reaches a constant temperature. Then bubbles are generated in theink rapidly so as to bring the interface of the cavitation-resistantfilm 7 into a condition not to contact the ink directly. Consequently,the heaters 5 and the cavitation-resistant film 7 increase temperaturerapidly due to the condition not to contact the ink directly (conditionII). In a lapse of a constant time, supply of electric energy to theelectrothermal transducing member is stopped (timing to supply anapplication stop signal te). Then the temperature of the heaters 5 andthe cavitation-resistant film 7 drops gradually. Consequently, thebubbles in the ink disappear to bring the ink and the interface of thecavitation-resistant film 7 back to the initial contact condition.

On the other hand, in the case of the non-discharge, on and after thepoint of time when electric energy is applied to the electrothermaltransducing member (timing to supply an application start signal t0),the temperature of the cavitation-resistant film 7 rises rapidly. Forexample, in the case of occurrence of ink non-discharge due to cloggingof the flow channel with the bubbles, the ink and the interface of thecavitation-resistant film 7 are brought into a condition not to contacteach other directly. Therefore, the temperature of the interface of thecavitation-resistant film 7 rises more rapidly than in the case of thenormal discharge. In a lapse of a constant time, supply of electricenergy to the electrothermal transducing member is stopped (timing tosupply an application stop signal te). Then the temperature of theheaters 5 and the cavitation-resistant film 7 drops gradually.

Next, the temperature changes detected with the temperature detectingelement 3 will be described when the heaters 5 undergoes on and offoperations.

FIG. 4 is a condition chart illustrating temperature profiles in thetemperature detecting element 3. FIG. 4 illustrates the temperatureprofiles in the case where ink is discharged normally and in the case ofink non-discharge respectively. Both of the temperature profilesillustrate the result obtained by temperature simulation with acomputer.

In FIG. 4, the time t0 is timing when the application start signal issupplied. The time te is timing when the application start signal issupplied and is set to the timing in 0.8 μsec after the time t0. Theheaters 5 are electrothermal transducing members with a resistant valueof 200Ω and are driven by a pulse drive signal of 18 V. The drivecondition for those heaters 5 is basically the same as temperaturesimulation in FIG. 3.

In both cases of normal discharge and non-discharge, at the time tp insubstantially 1.2 μsec from the timing te, the temperature value reachesthe maximum temperature of the peak. The time period from the timing teup to the timing tp when the temperature value reaches a peak is a delayin the process of transmitting the heat generated by the heaters 5 tothe temperature detecting element 3. The delay time thereof is 1.2 μsecand is small. The result thereof tells that the temperature detectingelement 3 has a rapid response property. That is a characteristicobtained by the structure with the temperature detecting element 3 beingarranged immediately below the electrothermal transducing members(heaters 5) (the Si substrate side) through the interlayer insulatingfilm 4 having substantially 1.3 μsec thickness.

In addition, the temperature peak value T_(G) in the case of a normaldischarge is 218° C. The temperature peak value T_(NG) in the case ofnon-discharge is 260° C. The balance between the both temperature peakvalues is 52° C. Thus, the balance between the temperature peak valuesat the time of normal discharge and at the time of non-discharge issufficiently large. Therefore, setting the standard temperature valueTref between the temperature peak value T_(NG) and the temperature peakvalue T_(G), it is possible to precisely determine the respectiveconditions of the normal discharge and the non-discharge. That is acharacteristic obtained by the structure with the temperature detectingelement 3 being arranged immediately below the electrothermaltransducing members through the interlayer insulating film betweenlayers 4 having substantially 1.3 μm thickness as described above.

Next, in order to search for the optimum arrangement position of thetemperature detecting element 3 on the heater 5, a computer was used tocarry out simulation. FIGS. 5A and 5B illustrate temperature profilesincluding temperature drops in respective positions apart in thedirection along the surface of the Si substrate and temperature drops inrespective positions apart in the direction perpendicular to the surfaceof the Si substrate obtained by simulation with a computer.

FIG. 5A simulates temperature in a position apart from the heater centerin the direction of the heater side along the Si substrate surface. Thepositions located at +12 μm and located at −12 μm from the center of theheater are equivalent to the heater end portions.

In addition, FIG. 5B simulates the temperature in respective positionswith the direction apart from the Si substrate as positive in thedirection perpendicular to the surface of the Si substrate from thecenter of the bottom surface of the heater. FIG. 5B is a temperatureprofile on the Si substrate side (the position to become negative interms of distance from the heater).

The simulation hereof will be described in details below.

In the substrate temperature profile in planar direction in FIG. 5A,temperature drops rapidly in the heater circumferential portion(position approximately at 15 μm from the heater center), thetemperature remain low, giving rise to few temperature shifts. Thistells that in the case of arranging the temperature detecting elementsin the position as in FIG. 16 describing a prior art (the positionextending sideway toward along the substrate plane toward the heater)does not enable detection of rapid and precise heater temperature.Moreover, in the future, accompanied by heaters being highly denselyarranged, it will be difficult to secure the space to arrange thetemperature detecting elements. In addition, it is apparent thatconsideration of constraints and the like on adjacent arrangement ofheaters and temperature detecting elements due to various circumstancessuch as photoprocess resolution and the like at the time of fabricationdoes not enable arrangement, sideway of the heaters, of the temperaturedetecting elements enabling exact detection of temperature.

In addition, the temperature profile in cross-sectional direction of thesubstrate in FIG. 5B illustrates temperature dropping approximatelylinearly from the bottom plane of the heaters to the position (−2.8 μm)of approximately 2.8 μm toward the Si substrate side to thereafter reachconstant temperature. That simulation employs an SiO₂ layer from 0 μm to−2.8 μm to an Si layer (Si substrate) from the position of −2.8 μm. Anactual head substrate includes 1 μm to 2 μm insulating film betweenlayers and a several-thousand Å heat accumulating layer thereunder. AnSi substrate is present below the heat accumulating layer, where asemiconductor element for heating to drive heaters corresponding withink discharge signals (see FIG. 1). The present simulation has beenimplemented with the temperature detecting element having been arrangedat the position of −1.4 μm. The result thereof tells that the case ofthe temperature detecting element being arranged inside the Si substratedoes not enable rapid response and preciseness for detecting defectivedischarge each for discharge timing on the level to be detected in thepresent embodiment.

The present embodiment includes the temperature detecting element 3arranged apart from the heaters 5 intermediated by an interlayerinsulating film 4 in the position below the heaters 5 and above the heataccumulating layer 2 (in the position nearer the heaters). Moreover, thetemperature detecting element 3 is arranged immediately below theheaters. There, immediately below refers to mutual positional relationso as to stack at least the heaters 5 and the temperature detectingelements in the direction perpendicular to the surface of the substrate.More preferably, such relation so as to bring the central positions ofthe heaters and the temperature detecting element into correspondence isbetter. There, the heat accumulating layer 2 is a type of heatinsulating layer provided under the heaters 5 (on the Si substrate side)in order to transmit heat energy generated by the heaters 5 to the inkin the ink flow path above the heaters 5. Therefore, the temperaturedetecting elements 3 are arranged in the position upper than the heataccumulating layer 2 (closer to the heaters) as that heat insulatinglayer.

The result thereof tells that the temperature detecting elements 3 arearranged below the heaters 5 (on the substrate side), that is, beyondthe heaters 5 and between the heaters 5 and the heat insulating layer(heat accumulating layer 2) via the interlayer insulating film 4 as aninsulating layer, thereby enabling temperature detection including rapidresponsiveness and preciseness.

Here, it is apparent that a configuration to arrange the temperaturedetecting elements inside the Si substrate or on the rear surface of theSi substrate with several hundred μm thickness as comparison enablesdetection of temperature changes over the head after head drive forseveral minutes but not further. In addition, the configuration with thetemperature detecting elements arranged sideways of the heaters islikewise. In any event, it is extremely difficult for the configurationto be treated as comparison to detect and determine temperatureinformation corresponding with each nozzle rapidly each for dischargetiming.

Next, a temperature detecting circuit for detecting temperature througha heat controlling circuit for controlling the drive of the heaters 5and the temperature detecting element 3 will be described.

FIG. 6 is a block diagram illustrating a schematic configuration of aheater controlling circuit and the temperature detecting circuit appliedto the recording head illustrated in FIG. 1 and FIG. 2. With referenceto FIG. 6, individual wiring 31 and 32 connected to each terminal of thetemperature detecting element 3 configures a part of a temperaturedetecting circuit for detecting temperature information from thetemperature detecting element 3. The temperature detecting circuit has aconstant current circuit 35 for supplying the temperature detectingelement 3 with constant current and a voltage detection circuit 37 fordetecting voltage generated between the individual wiring 31 and 32.

The heater controlling circuit has an AND circuit 36 a for controllingthe drive of the heaters 5. One terminal of the individual heater 5 isconnected to the ground line GNDH via the switching element 38 (an nMOStransistor, for example). The other terminal is connected to a voltagesupplying line VH. The AND circuit 36 a takes a heater applied signalHE, a block selection signal BLE and a stored data DATA as an inputrespectively to derive logical multiplication of those inputs. Outputsof the AND circuit 36 a are supplied as a switching element controllingsignal to the switching element 38 via the amplifying circuit 39.

FIG. 7 is a timing chart illustrating operations of the heatercontrolling circuit illustrated in FIG. 6. The block selection signalBLE designates one bit selection period. The stored data DATA is set totake a high level (corresponding with “1”) for the one bit selectionperiod. Therefore, for the period with the block selection signal BLEbeing on a high level, the outputs of the AND circuit 36 a will reach ahigh level. For the period with the outputs of the AND circuit 36 abeing on a high level, the switching element 38 is put on to supply theheater 5 with voltage.

The heaters 5 transduce electric energy to heat energy. With the heatenergy from that heater 5, the temperature detecting element 3 providedimmediately below the heaters 5 generates temperature changes accordingto the temperature profiles illustrated in FIG. 4. Based on the voltagevalue detected by the voltage detection circuit 37, information(temperature information) corresponding with temperature changes intemperature detecting element 3 thereof is obtainable.

The above described heater controlling circuit and the temperaturedetecting circuit may be formed on the Si substrate 1 illustrated inFIG. 1 or may be formed on a substrate different from the Si substrate1.

Temperature information is obtained from the output signals (detectedvoltage) of the voltage detection circuit 37 to enable determination onwhether a non-discharge state occurs or not based on that obtainedtemperature information. The determination on the non-discharge state isimplemented based on the reference temperature value Tref illustrated inFIG. 4. Specifically, the case where the detected temperature value ofthe temperature detecting element 3 obtained based on the output signalsof the voltage detection circuit 37 exceeds the preset referencetemperature value Tref is determined to be a state of non-discharge. Thecircuit for determining the state of that non-discharge may be formed onthe Si substrate 1 illustrated in FIG. 1 or may be formed on a substratedifferent from the Si substrate 1.

Next, applying the temperature detecting circuit illustrated in FIG. 6,a circuit for outputting the determination signal presentingnon-discharge will be described. FIG. 8 illustrates the configuration ofthat circuit.

The circuit illustrated in FIG. 8 is provided with a comparator 39replacing the voltage detection circuit in the circuit illustrated inFIG. 6. An “−” side input (inverting input) of the comparator 39 isconnected to the line to which the individual wiring 32 is connected.The “+” side input (non-inverting input) of the comparator 39 isprovided with reference voltage Vref.

The comparator 39 brings voltage Vt (temperature information) suppliedto the side “−” input and the reference voltage Vref supplied to the “+”side input into comparison. In the case where the voltage Vt exceeds thereference voltage Vref, the comparator 39 outputs a determinationsignal. The reference voltage Vref is voltage corresponding with thetemperature Tref described in FIG. 4. The voltage Vt (temperatureinformation) is voltage corresponding with the temperature of detectingelement T illustrated in FIG. 4.

In the case of normal discharge, Vt≦Vref will be obtained. On the otherhand, in the case of the non-discharge, Vt>Vref will be obtained.

The comparator circuit 39 may be formed on the Si substrate 1illustrated in FIG. 1 or may be formed on a substrate different from theSi substrate 1.

In addition, the reference voltage Vref supplied to the “+” side inputof the comparator circuit 39 may be a fixed value or may be a variablevalue following environmental temperature and a temperature change atthe time of driving. In any case, the value of the reference voltageVref is set in consideration of the relation among the temperature Tref,the temperature peak value T_(G) in the case of the normal discharge andthe temperature a temperature peak value T_(NG) in the case ofnon-discharge respectively illustrated in FIG. 4.

As described above, according to the present embodiment, arrangement ofthe temperature detecting element immediately below the electrothermaltransducing member to sandwich the insulating layer can configure atemperature detecting circuit with rapid responsiveness and little delayand can realize a circuit enabling precise determination on the statesof normal discharge and non-discharge. Within the range withoutdeparting the gist hereof, the configuration and operations of thestorage apparatus of the present embodiment can be modifiedappropriately.

For example, the temperature detecting element 3 may be a linearresistor pattern presenting a shape with a plurality of folds(hereinafter to be referred to as “snake shape”) as illustrated in FIG.9. The case of using a square-shaped temperature detecting element 3 asillustrated in FIG. 2 can form a flat plane shape for the heaters 5formed on the temperature detecting element 3 to sandwich the insulatingfilm between layers 4 and can improve stability of discharge operations.In contrast, the case of using the snake shaped temperature detectingelement 3 as illustrated in FIG. 9 can set larger resistance vale in thetemperature detecting element 3 and therefore enables more accuratedetection on micro temperature changes.

Second Embodiment

FIG. 10 is a plan view of a recording head mounted on a recordingapparatus being a second embodiment of the present invention. In FIG.10, a discharge nozzle portion including a discharge port, a liquidroute and the like is omitted.

The recording head of the present embodiment is obtained by replacingthe individual wiring 32 with a common wiring 33 in the recording headillustrated in FIG. 2 and has a stacked structure likewise the oneillustrated in FIG. 1. The thin film resistor member included in thetemperature detecting element 3 is formed separately and independentlyimmediately below the electrothermal transducing member included in eachof heaters 5. Here, the arrangement position of the temperaturedetecting element 3 is the optimum position obtained as a result ofsimulation on the above described first embodiment.

An end (terminal) of the temperature detecting element 3 is connected toindividual wiring 31. The other end (terminal) is connected to commonwiring 33. The individual wiring 31 and the common wiring 33 made of Aland the like and is formed together with the temperature detectingelement 3 on the Si substrate.

According to the recording head of the present embodiment, in additionto the characteristic of the first embodiment, the other terminal of thetemperature detecting element 3 is structured to include common wiring,giving rise to an advantage in layout so as to enable simplerconfiguration of the wiring layer. In addition, time-division outputtingof outputs (temperature information) from a plurality of temperaturedetecting elements 3 is enabled to give rise to an advantage insimplifying information processing.

Next, a temperature detecting circuit for outputting time-divisionoutputting of outputs (temperature information) from the temperaturedetecting elements 3 will be described.

FIG. 11 is a block diagram illustrating a schematic configuration of acontrol circuit and a temperature detecting circuit applied to therecording head illustrated in FIG. 10. With reference to FIG. 11,individual wiring 31 connected to one terminal of the temperaturedetecting element 3 is connected to the line provided with voltage VSSvia the switching element 34. A constant current circuit 35 forsupplying the temperature detecting element 3 with constant current 35and a voltage detection circuit 37 for detecting voltage are connectedto the line provided with the voltage VSS and each of the temperaturedetecting elements 3 respectively. The individual wiring 31 and thecommon wiring 33 configure a part of a temperature detecting circuit.

One terminal of the individual heater 5 is connected to the ground lineGNDH via the switching element 38. The other terminal of the individualheater 5 is connected to a voltage supplying line VH. The switchingelements 34 and 38 include nMOS transistors, for example.

The controlling circuit 36 is provided to each of the discharge nozzles(discharge ports) including the temperature detecting element 3 and theheater 5. The controlling circuit 36 controls the switching element 34connected to the temperature detecting element 3 and the switchingelement 38 connected to the heater 5 and includes two AND circuits 36 aand 36 b. The AND circuit 36 a takes a heater applied signal HE, a blockselection signal BLE and a stored data DATA as an input respectively toderive logical multiplication of those inputs. The AND circuit 36 btakes a block selection signal BLE, a print data DATA and a signal PTEas an input respectively to derive logical multiplication of thoseinputs. Outputs of the AND circuit 36 a are supplied as a switchingelement controlling signal to the switching element 38 via theamplifying circuit 39. Outputs of the AND circuit 36 b are supplied as aswitching element controlling signal SWE to the switching element 34.

FIG. 12 is a timing chart illustrating operations of the control circuit36 illustrated in FIG. 11. The block selection signal BLE designates onebit selection period. The stored data DATA is set to take a high level(corresponding with “1”) for the one bit selection period. Therefore,for the period with the block selection signal BLE being on a highlevel, the outputs of the AND circuit 36 a will reach a high level. Forthe period with the outputs of the AND circuit 36 a being on a highlevel, the switching element 38 is put on to supply the heater 5 withvoltage.

The switching element controlling signal SWE being the outputs of theAND circuit 36 b will reach a high level for the period with the signalPTE being on a high level. For the period with the outputs of thatswitching element controlling signal SWE being on a high level, theswitching element 34 comes into the on state. The switching element inthe on state is connected to the temperature detecting element 3, whichis provided with current from the constant current circuit 35. Thevoltage detection circuit 37 detects voltage corresponding with theresistance value of the temperature detecting element 3.

The heaters 5 transduce electric energy to heat energy. With the heatenergy from that heater 5, the temperature detecting element 3 providedimmediately below the heaters 5 to sandwich the insulating layergenerates temperature changes according to the temperature profilesillustrated in FIG. 4. Thereby, based on the voltage value detected bythe voltage detection circuit 37, information (temperature information)corresponding with temperature changes in temperature detecting element3 thereof is obtainable.

The temperature detecting circuit illustrated in FIG. 11 generates aswitching element controlling signal SWE so that each of the switchingelements 34 is switched to the on state sequentially. Thereby, thevoltage detection circuit 37 will output a signal corresponding withtemperature information from each of the switching elements 34 in atime-division state.

The temperature detecting circuit and the controlling circuit may beformed on the Si substrate 1 illustrated in FIG. 1 or may be formed on asubstrate different from the Si substrate 1.

Also in the present embodiment, temperature information of thetemperature detecting element 3 connected to each of the switchingelements 34 is obtained from the output signals of the voltage detectioncircuit 37 to enable determination on whether a non-discharge stateoccurs or not based on that obtained temperature information. Thedetermination on the non-discharge state is implemented based on thereference temperature value Tref illustrated in FIG. 4. Specifically,the case where the value of the switching element 34 obtained based onthe output signals of the voltage detection circuit 37 exceeds thepreset reference temperature value Tref is determined to be a state ofnon-discharge. The circuit for determining the state of thenon-discharge may be formed on the Si substrate 1 illustrated in FIG. 1or may be formed on a substrate different from the Si substrate 1.

Next, applying the circuit illustrated in FIG. 11, a circuit foroutputting the determination signal presenting non-discharge will bedescribed. FIG. 13 illustrates that circuit configuration.

The circuit illustrated in FIG. 13 includes a comparator 39 for each ofthe controlling circuits 36 in addition to the circuit illustrated inFIG. 11. An “-−” side input of that comparator 39 is connected to thecommon wiring 33 to which the other terminal of the temperaturedetecting element 3 is connected commonly. The “+” side input of thecomparator 39 is provided with reference voltage Vref. The comparator 39outputs a determination signal.

The comparator 39 brings voltage Vt (temperature information) suppliedto the “−” side input and the reference voltage Vref supplied to the “+”side input into comparison and outputs a determination signal based on acomparison result thereof. The reference voltage Vref is voltagecorresponding with the temperature Tref described in FIG. 4. The voltageVt (temperature information) is voltage corresponding with thetemperature of detecting element T illustrated in FIG. 4.

In the case of normal discharge, Vt≦Vref will be obtained so that thedetermination signal is set to the high level (or the signal level on“+” side). In the case of the non-discharge, Vt>Vref will be obtained sothat the determination signal is set to the low level (or the signallevel on “−” side).

The comparator circuit 39 may be formed on the Si substrate 1illustrated in FIG. 1 or may be formed on a substrate different from theSi substrate 1.

In addition, the reference voltage Vref supplied to the “+” side inputof the comparator circuit 39 may be a fixed value or may be a variablevalue following environmental temperature and a temperature change atthe time of driving. In any case, the value of the reference voltageVref is set in consideration of the relation among the temperature Tref,the temperature peak value T_(G) in the case of the normal discharge andthe temperature a temperature peak value T_(NG) in the case ofnon-discharge respectively illustrated in FIG. 4.

Also in the above described present embodiment, arrangement of thetemperature detecting element immediately below the electrothermaltransducing member can configure a temperature detecting circuit withrapid responsiveness and little delay and can realize a circuit enablingprecise determination on the states of normal discharge andnon-discharge. Within the range without departing the gist hereof, theconfiguration and operations of the storage apparatus of the presentembodiment can be modified appropriately.

For example, the temperature detecting element 3 may be a linearresistor pattern presenting a shape with a plurality of folds, that is,so-called snake shape as illustrated in FIG. 14. The case of using asquare-shaped temperature detecting element 3 as illustrated in FIG. 10can form a flat plane shape for the heaters 5 formed on the temperaturedetecting element 3 to sandwich the interlayer insulating film 4 and canimprove stability of discharge operations. In contrast, the case ofusing the snake shaped temperature detecting element 3 as illustrated inFIG. 14 can set larger resistance vale in the temperature detectingelement 3 and therefore enables more accurate detection on temperaturechanges on a micro-level.

In addition, a configuration as illustrated in FIG. 15 may be taken soas to transduce temperature detected through the temperature detectingelement 3 to digital values. In such a case, the voltage detectioncircuit 37 of the circuit illustrated in FIG. 11 is replaced by an ADconverter 37 a. The input of the AD converter 37 a is connected to thecommon wiring 33. The controlling circuit 36 controls each of theswitching elements 34. Thereby information of detected temperatureobtained by each of the temperature detecting elements 3 is output fromthe AD converter 37 a on a time-division basis. The configuration withsuch an AD converter 37 a gives rise to an advantage in improvement innoise immunity.

The above described circuit outputting the determination signals and ADconverter can be mounted on any of the recording head and the recordingapparatus to form an embodiment.

Any of the above described embodiments generates an application stoppagesignal in the non-discharge case to enable a stoppage of signal supplyto the heaters.

While the present invention has been described with reference toexemplary embodiments, it is to be understood that the invention is notlimited to the disclosed exemplary embodiments. The scope of thefollowing claims is to be accorded the broadest interpretation so as toencompass all such modifications and equivalent structures andfunctions.

This application claims the benefit of Japanese Patent Application No.2006-098674, filed Mar. 31, 2006, and 2007-066591, filed Mar. 15, 2007which are hereby incorporated by reference herein in their entirety.

1-14. (canceled)
 15. A liquid discharge head comprising: a plurality ofheat elements for generating thermal energy used for discharging theliquid; a plurality of temperature detecting elements connected to eachother in parallel to detect a temperature, each of the temperaturedetecting elements being provided in a position corresponding to one ofthe heat elements; a plurality of switching elements, each of theswitching elements being used for selecting one of the temperaturedetecting elements; and a temperature detecting circuit used fordetecting temperature information from the selected temperaturedetecting elements.
 16. A liquid discharge head according to claim 15,further comprising a plurality of second switching elements, each of thesecond switching elements being used for selecting one of the heatelements; and a control circuit for controlling the switching elementand the second switching element corresponding to one of the heatelements in synchronism with each other.
 17. A liquid discharge headaccording to claim 16, wherein the control circuit includes a firstportion for forming a first control signal for controlling each of theswitching elements using a selected signal and outputting the firstcontrol signal to each of the switching elements, and a second portionfor forming a second control signal for controlling each of theswitching elements using the selected signal and outputting the secondcontrol signal to each of the switching elements.
 18. A liquid dischargehead according to claim 15, wherein each of the temperature detectingelements is a resistance element comprising a material of which aresistance value varies in accordance with the temperature.
 19. A liquiddischarge head according to claim 18, wherein the temperature detectingcircuit includes a voltage detecting circuit for detecting a voltageapplied to the resistance element.
 20. A liquid discharge head accordingto claim 15, wherein the temperature detecting circuit detects thetemperature information by time-division from the temperature detectingelements.
 21. A liquid discharge head according to claim 15, furthercomprising a comparing circuit for comparing the temperature informationoutputted from the temperature detecting circuit and information of apreliminarily determined reference temperature.